Megafauna Survival in Southeast Asian Landscapes Varies

The presence of humans is detrimental to megafauna survival, and humans are responsible for the extinctions and extirpations of many species across the globe. Furthermore, in regions where megafauna still survives, humans depress their overall populations with hunting and habitat degradation. A new study of megafauna in Southeast Asia analyzes the differences in species survival rates in the presence of human impact. An impressive assemblage of megafauna still survives in the region despite a continuous and growing human presence. Humans have lived in the region for 60,000 years. The region enjoys a rich tropical climate with an abundance of food sources and variety of habitats that support megafauna populations. The authors of the study set up camera traps at many sites in Thailand, Malasia, Singapore, and parts of Indonesia. They recorded the abundance of 14 species including tiger, leopard, clouded leopard, dhole, sun bear, sambar deer, Malay tapir, Sumatran rhinoceros, Asian elephant, wild boar, bearded pig, mainland serow (a species of tropical goat), and banteng and guar–2 species of wild cattle. Wild boar was the most common species and was found at 65% of the sites. Sumatran rhinos were the least common species and were not found at all. The study considers Sumatran rhinos to be functionally extinct. Banteng and guar were among the less common species as well. People like to eat their beef. No 2 sites had identical species assemblages demonstrating the varied response of megafauna to human presence.

Megafauna populations decline or are extirpated in regions where they suffer from human hunting and habitat degradation. Some megafauna species in southeast Asia follow this trend, but others defy it. The reasons for this disparity are complex and poorly understood. Chart from the below reference.
Chart showing body size and whether a species was herbivore or carnivore didn’t matter in the frequency of extirpations at different sites in Southeast Asia. Charts also from the below study.

The authors of the study note 74 extirpations of megafauna that formerly ranged throughout the region. 58 extirpations occurred during the Holocene from 11,700 years ago to 1950. 16 extirpations have occurred in the region during the Anthropocene (since 1950). (Scientists don’t agree among themselves about when the Anthropocene began. The Anthropocene is regarded as the time when humans became the dominant force in earth’s environment. Some scientists think it should be considered as beginning in 1611, while others believe 1950 should be the starting date. Still others think the Anthropocene began 50,000 years ago. This study goes by the 1950 date.) They found no pattern for megafauna survival or failure to survive. Size didn’t matter nor did whether or not they were a carnivore or herbivore. Some species actually favored areas where habitat was degraded. Wild boars thrive near human habitations. They benefit from foraging on farmer’s crops, and the local Muslims won’t hunt them because they don’t eat pork. Asian elephants, tigers, and clouded leopards were also common in degraded habitats. However, the most disturbed sites had 2.5 times more extirpations than the least disturbed sites. There is some good news: as long as anti-poaching regulations are enforced, megafauna can survive near human settlements. Unfortunately, large, protected parks in remote areas are hard to patrol, and megafauna can become extirpated in areas that otherwise offer excellent habitat.

Reference:

Amir, Z.; J. Moore, P. Negret, and M. Irvin

“Megafauna Extinctions Produce Idiosyncratic Anthropocene Assemblage”

Science Advances 8 (42) Oct 2022

https://www.science.org/doi/10.1126/sciadv.abq2307

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